Ferrite composition containing titanium and nickel



May 2, 1961 J. M. BROWNLOW FERRITE COMPOSITION CONTAINING TITANIUM AND NICKEL Filed Dec. 30, 1957 s 2 R 1 EL B M ZJ U 1 N 4 m 1. A :0 1 1 8 L D m H K mM M0 B 4 MW m K 4| 1 KK K 9-70 0 6 M M l B KK K K A 0 2 0 T O W A 1 0 s mm 6. B 0 W m 1 N 0 1 M 8 m 0 A ATOM NUMBERS SYSTEM M 'Fe 'Ti |NVENTOR JAMES M. BROWNLOW AGENT United States Patent 2,982,782' FERRI'IE COMPOS N CONTAINING TITANIUM t NICKEL j James M. Brownlow, Poughkeepsie, N.Y., assi or to Intel-national Business Machines Corporation, ew York, N.Y., a corporation of New York Filed Dec. 30,1957, Ser. No. 706,176

' ,fs (Cl. 252-525) ceramic procedures used in the preparation of. the. fer-' rospinel, certain' exacting sinteririg' conditions have been necessary .to prepare manganese containing ferrospinels 1;: ing moldinghvmhe mixture isicompactedfino a Stelvdie with suflicient pressure to form a clos'ely'coherentilbody,

with any degree of reproducibility' The present system has been found to provide a square loop ferrite having the requisites for operation as a memory storageele ment and at the same time is readily adaptable to standard ceramic techniques and procedures for fabrication of memory cores.

An object of this invention is to provide a square loop ferrite having certain improved magnetic characteristics.

A further object of this invention is to provide a ferromagnetic memory storage core of the rectangular hysteresis loop type, which is capable of being prepared by more simplified sintering techniques than those hitherto required for similar systems containing manganese oxide.

Still another object is to provide'a square loop ferrospinel having the composition Mg-Ni-Ti ferrite.

An object of this invention is to provide a square loop ferrospinel which has a zero magnetostrictive effect.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawing, the figure is a triaxial diagram for the chemical system Fe--TiM, where M is Mg/a or Ni/ (1-a) and a ranges from 0.45 to 0.91. The area bounded by 'A--B--C-D is the preferred Working range in this system. I

By virtue of theoretical considerations and subsequent experimentation applicant has determined that the oxides of the tetravalent ion, Ti and the divalent ion,"Ni could be combined with magnesium oxide andferric oxide to produce a ferrospinel whose magnetic character- 2 2,982,732 Patented May 2, 1961 TABLE I Composition (atom numbers) Code No Fe Mg Ni T1 0 Br/Bs 1.80 0.98 0.10 0.12 0.01 0.75 1.80 0.88 0.20 0.12 0.82 0. 86 1.80 0.58 0.50 0.12 0.54 0.70 1.62 1.08 0:10 0.20 0.01 0.81 1. 62 1. 08 0. 0. 0. 87 0. 81 1.62 0.90 0.18 0.20 0. 85 0.86 -1. 62 0.94 0.24 0.20 0.79 0.73 1.62 090 0.28 0.20 0.76 0. 91 1.60 1.00 0.20 l 0.20 0.83 0.84 1. 78 1. 22 0. 00 0. 10 1. 00 0. 72 1. 50 0. 00 0. 30 0. 30 0. 75 0.80 1.70 0.50 0.60 0.80 0.45 0.59 1. a0 0. 70 0. 60 0. 40 0. 54 0.70 1.72 0.90 0.18 v 0.18 0.70 0.70 1.58 1.02 0.20 0.20 0.84 0.76 1.72 0.95 0.17 0.15 0.85 0. 70

A preferred manner of preparing the ferrites of the present invention is the following: The ferrite powders are calcined at a temperature of approximately 1000 C. for a period of onetotwo hours and thoroughly mixed so as to-form a homogeneous mixture of predetermined proportions. The mixtureis subsequently ground istics were suitable for operation in bistable memory systerns.

In Table I the datarepresented'in the triaxial-diagram of the figure is compared with compositions'in which the number of atoms of Ti and of Fe have been held constant while the relative amounts. ofZthe other two constituents .have been varied. The hysteresis loop square ness ratio, Br/ Bs, is also given for each composition.

so that the largest grain sizeis less than ten microns and a small percentagev of. lubricant material such as a monocrystalline wax or magnesium stearate and polyvinyl alcohol is added to reduce skin'friction and warping durusually greater than 40,000 pounds per square inch. The pressed body is then calcined at 800-1000 C. to drive oif the binder materials and moisture. The presintered body thus produced is enclosed in the covered receptacle as described, heated at 10001650 C. in air for from 10 minutes to 24 hours, furnace cooled to about 850C. during an additional 5-60 minutes and finally quenched to room temperature.

The pulse test data given in Table II is for Code No. Kl32-2. which was prepared by firing the oxide constituents at 1380 C. for 30 minutes, cooling to 1150 C. for 30 minutes in C0 and quenching to room temperature.

Applicant has discovered that the addition of even small amounts of Mn to the system of this invention results in a ferrospinel having a substantially reduced squareness ratio. Thus, as shown in Table III the incorporation of 0.13 atom of Mn in the base system has proven to be quite harmful.

" I TABLEIII obdeNo- Fe Mg 2 Ni [I'Ifi' 0, Mn Br/Bs Other divalent cations have beensubstituted for Ni t; v .in, thisv system, including .Zn+ and Cu- V I I Moreover, C1137!- orl kl fmay, also be substituted inpartfor Fe3r- The ferrite materials of this invention are suitable for application as memory elements in computer mechanisms and as ferrite cores in other selective logical applications. In addition, certain measurements of magnetostriction indicate that this parameter is zero over a range of compositions in this systein. For example, when radial stress was applied to the. ferrite. composition designated as K132-2 in Table I' no "change was observed in the hysteresis loop. Similar treatment of core compositions K13-2-3 and K132 resulted only --in--a slight --increase-a-nd decrease, respectively, in the squareness of the loop. Such unique -magnetic properties, hitherto unavailable in other square loop ferrospinels, indicates the extreme stability of this system towards changes in applied stress during actual computeropera'tion.

-Wh.ile there have been shown and described and pointed out the fundamental novel features of the invention as applied to. a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details {of the device illustrated and in its operation-may be made by those skilledin the art'wit h- 3 out departing from the spirit of the invention. It is the intention therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is: y

1 A rectangular hysteresis loop ferrospinel system consisting essentially of Mg Ni Ti 5e 0,; where w varies.- fror n 0.70 to 1.22, ;x from 0.01 to 0.60, y from 0.1.0 to 0.40 and z from 1.30 to -1.80,'said ferrospinel having a Br/Bs ratio of greater than 0.7.

2. A rectangular hysteresis ferrospinel consistingessentially of Mgo goNiojgTimzoFel204, said ferrospinel having a Br/Bs ratio-of 0.86.

3. A rectangularhysteresis ferrospinel consisting BS7 5 f M :maN mo mo rasa t fel'l'ospiflel having a -Br/Bs ratio 0130.81. Y

2,es2,7s2 4 A,

4 4. The product formed by heating a mixture of magnesium oxide, nickel oxide, titanium oxide and ferric oxide in such molecular percentages as to form a rectangular hysteresis loop ferrospinel having the formula Mg Ni Ti Fe O where w varies from 0.70 to 1.22, x from 0.01 to 0.60, y from 0.10 to 0.40 and z from 1.30 to 1.80, at temperatures Within the range 1000-1650" or 15 minutes to 24 hours, said product having a Br/Bs ratio of greater than 0.7.

5. The product formed by'heating a mixture of magnesium. oxide, nickel oxide, titanium "oxide and -ferric oxide in such molecular percentages as to form a rectangular hysteresis loop ferrospinel having the formula furnace cooling to 1150 for minutes in CO5 and quenching to room temperature.

References Cited in the file of this patent UNITED STATES PATENTS 2,565,861 Leverenz et a1. Aug. 28, 1951 2,579,978 Snoek et al Dec. 25., 1951 2,659,698 Berge Nov. 17,1953 2,736,708 Crowleyet a1. Feb. 28, 1956 1 FOREIGN PATENTS 697,219 Great Britain Sept. 19, 1953 735,375 Great Britain Aug. 17, 1955 737,284 GreatiBritain Sept. 21, 1955 30 OTHER REFERENCES Verwey: Aengewandte Chemie, Apr. 7, 1954, pages 189-192. 'Gorter: Philips Research Reports, December 1954, pages 403-418.

Econ'omos: J. AmeLCeramic Soc.,'1uly 1955,: page 

1. A RECTANGULAR HYSTERESIS LOOP FERROSPINEL SYSTEM CONSISTING ESSENTIALLY OF MGW, NIX, TIY, FEZO4 WHERE W VARIES FROM 0.70 TO 1.22, X FROM 0.01 TO 0.60, Y FROM 0.10 TO 0.40 AND Z FROM 1.30 TO 1.80, SAID FERROSPINEL HAVING A BR/BS RATIO OF GREATER THAN 0.7. 